“I hope you can let this go,’’ Trump said, according to the Comey notes, which were described by associates. Comey’s written account of the meeting is two pages long and highly detailed, the associates said. The details of Comey’s notes of the meeting were first reported by the New York Times.

Officials have previously said that Trump and his senior staff have been pressing the FBI to prioritize leak investigations over the bureau’s ongoing probe into possible coordination between Russian officials and Trump associates. On Tuesday, people close to the matter said Comey kept detailed notes of his multiple conversations with Trump.

That last sentence should strike fear into the White House. This one story is significant enough and will lead to more allegations of Trump obstructing justice. Those allegations are already very much in the news thanks to Trump firing Comey — the man leading an investigation into his campaign's alleged ties to Russia — last week.

But the possible existence of a trove of Comey memos may be the real story here. Comey is known to be a pretty meticulous keeper of notes, and CNN's Jake Tapper just reported that Comey kept extensive notes of his conversations with Trump for the precise reason that they made him uneasy — presumably because of Trump making requests such as the Flynn one that crossed a line for Comey.

As the New York Times notes, these memos “are widely held up in court as credible evidence of conversations.” The Times pointed to that famous incident back during the George W. Bush administration when Comey testified that there had been a race to reach the bedside of an ill Attorney General John Ashcroft as the FBI and senior White House officials fought over warrantless wiretapping. When the White House disputed Comey's version, then-FBI Director Robert Mueller's contemporaneous notes were used as confirmation.

Rep. Adam B. Schiff (Calif.), the top Democrat on the House Intelligence Committee, is already calling for Comey's notes to be subpoenaed. If they do see the light of day, we could have a whole lot of stories like the one about the loyalty pledge and Trump asking Comey to shut down the Flynn investigation.

Update: And Rep. Jason Chaffetz (Utah), the Republican chairman of the House Oversight Committee, is also talking about subpoenas.

Chaffetz:"I do have ability to unilaterally issue subpoena if need be hopefully if memo exists they will turn it over voluntarily & swiftly"

The reason we've learned about the Flynn memo appears to be because Comey shared it with others who are providing its details to the news media now. Perhaps other memos weren't shared with others, or not with people who would leak their details to the press. And if those other memos do come to light and show similar exchanges with Trump, that's going to be very difficult for the White House to combat in the court of public opinion.

That's because the notes will have been written before Trump fired Comey, and before Comey had an ax to grind. At that point, the White House would basically have to argue that Comey created a fictitious paper trail without a clear motivation.

There are a lot of ifs and assumptions in the above. We don't know how extensive Comey's notes are, how many of these situations there may have been with Trump or what will come to light. But the prospect of those memos seeing the light of day has to be frightening for a White House that is already taking on water.

And for a president who issued a pretty outlandish threat last week, it's a remarkable turn of events.